We are currently using the environment variable GNOME_DESKTOP_SESSION_ID to detect if we are running a gnome desktop environment.
The above variable has been deprecated and is no longer used.
I am on unity and I do some dev libraries of gnome installed. Now even though my desktop environment is unity, since GNOME_DESKTOP_SESSION_ID is set in my environment, it is incorrectly detected as Gnome and this results in picard looking at the wrong place for icons.
This hampers the ui themeing.